JavaScript

Object.freeze in JavaScript

JavaScriptObjectsObject.freezeintermediate

What this snippet does

Frozen objects silently ignore writes in non-strict mode — use for constants like config objects you never want mutated.

Expected output

3000
localhost
true

Why practise typing this

Typing objects code builds muscle memory for the symbols and indentation JavaScript uses most, which prose-based typing tests never cover. DevType measures your words per minute and accuracy on this snippet and tracks the individual characters you mistype, so later lessons can target them.

More JavaScript practice

Browse all JavaScript snippets →